An advanced early warning technology for coral bleaching crisis based on the electrochemical biosensing of coral-symbiotic zooxanthellae eDNA

Abstract

The symbiotic zooxanthellae in corals are extremely sensitive to the marine environment, and corals bleach rapidly when the symbiotic zooxanthellae are detached from their coral hosts. Currently, ecological monitoring techniques face many problems in coral health assessment, especially coral reef destruction during sampling. In this paper, an electrochemical eDNA biosensor based on ECM/MoS₂ nanocomposites constructed with specific DNA probes was developed to detect the environmental DNA of free zooxanthellae at a low limit of detection (LOD = 0.223 pM) and limit of quantification (LOQ = 0.743 pM) under the experimentally optimized conditions, demonstrating excellent specificity and steadiness. Over and above, the electrochemical response of the biosensor to zooxanthellae DNA was significantly higher than that of other interferent targets, proving its high selectivity. On this basis, the dependability and precision of the biosensor were further verified by comparing the biosensor with ddPCR (P > 0.05, RSD < 5 %). Hence, this electrochemical biosensor can dynamically monitor community changes in zooxanthellae without destroying coral reefs and may serve as a non-invasive method for early warning of coral reef crises. The technique can also be upgraded with portable capabilities in future studies to provide greater convenience in the field analysis of coral bleaching.